Insert for vapor-permeable and waterproof soles

ABSTRACT

An insert for vapor-permeable and waterproof soles, which has a stratified and cohesive monolithic sheet-like structure, which includes a plurality of functional layers made of a polymeric material that is impermeable to water in the liquid state and permeable to water vapor. At least one functional portion of the insert for soles has such a thickness as to give it a penetration resistance of more than approximately 10 N, assessed according to the method presented in chapter 5.8.2 of the ISO 20344-2004 standard.

TECHNICAL FIELD

The present invention relates to an insert for vapor-permeable andwaterproof soles.

BACKGROUND ART

As is known, the portion of the foot that has the greatest perspirationeffect is the sole.

Therefore, the region of the shoe where moisture produced byperspiration can accumulate most is the interface between the sole ofthe foot and the sole of the shoe.

Here, the sweat that is produced saturates the air with moisture andmostly condenses, stagnating on the footbed.

Only a marginal fraction of the moisture produced by perspirationdiffuses to the sides of the upper and exits from them if they arevapor-permeable.

This effect of stagnation of perspiration in the plantar region isparticularly conspicuous in shoes that have a rubber sole; in such casesvapor permeation through the sole is in fact prevented by its totalwaterproofness.

As is known, the stagnation of sweat in the plantar region produces inthe user of the shoe a feeling of discomfort and constitutes apreferential location for the growth of bacterial cultures, whichnotoriously cause bad odors.

The need to obviate the stagnation of moisture produced by perspirationat the plantar region of shoes is therefore a commonly felt need.

A first attempt to meet this need consists of the solution disclosed inItalian patent no. 1232798.

The teaching contained in said patent consists in dividing the rubbersole into two layers, the lower of which has through micro-holes, and ininterposing between them a semipermeable membrane that is joinedperimetrically to the two layers, in order to avoid infiltrations ofwater and thus obtain a sole that is impermeable to water in the liquidstate and is permeable to water vapor.

For the sake of simplicity, hereinafter an element with the property ofbeing impermeable to water in the liquid state and permeable to watervapor is indicated as waterproof and vapor-permeable.

The semipermeable membranes that the inventor of Italian patent no.1232798 teaches to use are for example of the type described in U.S.Pat. Nos. 4,187,390 and 4,194,041 in the name of W. L. Gore or 6,228,477in the name of BHA Technologies.

These membranes are provided by means of thin films of expandedpolytetrafluoroethylene, e-PTFE, with thicknesses that generally varyfrom 15 to 70 microns, and are waterproof and vapor-permeable.

Their microstructure is characterized by the presence of dense areas,known as nodes, which are interconnected by elongated filaments, knownas fibrils.

These semipermeable membranes, initially conceived for the militarysector, have been developed and used in the field of clothing and shoesto avoid the accumulation of water vapor caused by perspiration in itemsof clothing and provide shoes with uppers with waterproof andvapor-permeable linings.

Since the market of the clothing and shoes sectors has always requiredsoft and comfortable items, in the described applications there is astrong need to make sure that the membrane, understood as a functionallayer, does not compromise these characteristics.

This requirement has developed into an actual technical prejudice, whichhas entailed the use of membranes provided in low thicknesses in orderto be laminated with support and/or aesthetic finishing materials, suchas fabric or leather, so as to obtain finished laminates that haveenhanced characteristics of flexibility, ease of bending, softness,surface slipperiness, compressibility and extensibility and low weightper unit surface.

However, the films that provide these membranes have poorcharacteristics of mechanical strength, indeed due to their lowthickness.

Indeed, it should be noted that the value of resistance of the laminatederives mainly from the characteristics of the layer of fabric or of thesupport with which the membrane is coupled.

In particular, available films of polymeric material, used to providesaid membranes as mentioned, have thicknesses generally from 15 to 70microns, which give them limited penetration resistance, i.e., less than5 N. The expression “penetration resistance” is used to reference thecharacteristic defined by a measurement performed according to themethod presented in the ISO 20344-2004 standard in chapter 5.8.2,“Determination of the penetration resistance of the sole” related tosafety shoes.

This limited mechanical resistance to penetration has led the inventorof said Italian patent no. 1232798 to prevent contact of the membranewith foreign objects by limiting the diameter of the holes of the solewhich the membrane faces.

However, this solution has proved to limit drastically the area of thesole assigned to vapor permeation.

The teaching contained in Italian patent no. 1282196 by the sameApplicant proposes a solution that is aimed at overcoming thesedrawbacks.

This patent discloses a shoe with a sole made of elastomer which isprovided with through holes and comprises a midsole that comprises awaterproof and vapor-permeable membrane superimposed on a protectivelayer, preferably made of felt, which is treated so as to bewater-repellent.

Since the protective layer is not waterproof, it is not possible toperform a direct seal of the midsole with the sole, but a perimetricwaterproof element is used which provides a sealing bridge between thewaterproof and vapor-permeable membrane and the sole. This invention,while allowing effective protection of the membrane against thepenetration of external objects, has some aspects that can be improved.

In particular, the connection of the protective layer to the membrane,in order to allow an effective protection thereof, must occur by way oftheir intimate adhesion.

For this purpose, adhesives and glues are used which, while not coveringall of the surface of the membrane, delimit the vapor-permeable portionof the part that they affect.

Moreover, the protective layer itself, though being vapor-permeable, isan obstacle to the passage of water vapor from the inside to the outsideof the shoe through the midsole.

This drawback increases when, during use of the shoe, the protectivelayer progressively loses its characteristics of water-repellence andtherefore tends to become impregnated with water and/or mud or othertypes of dirt, absorbed through the holes of the tread, compromising itsvapor permeability.

A drawback of both of said proposed solutions consists in that duringuse the cyclic flexing and traction to which the midsole is subjectedduring walking tends to cause progressive wear and tear of the membrane,thus causing a loss of waterproofness at the sole.

In order to obviate this drawback, Italian patent no. 1282196 teaches toprovide soles that have small holes, for example with dimensions of1.5-2.0 mm, that are sufficiently spaced so as to not compromise theirstructural stiffness.

In this manner, the sole supports the midsole rigidly enough to contrastthe tear of the membrane.

However, the portion of sole that can be crossed by water vapor islimited indeed by the rarity and narrowness of the holes with which itis provided.

A further solution, aimed at proposing a compromise between the need tocontrast the tear of the membrane and the need to allow effectivedisposal of water vapor produced by perspiration through the sole, isdescribed in Italian patent no. 1334928 by the same Applicant.

This patent discloses a sole having a structure that comprises asupporting layer which, at least in one macroportion, is made of mesh,felt or other diffusely perforated material.

A membrane made of material that is waterproof and permeable to watervapor is associated in an upward region with the supporting layer so asto cover at least the macroportion thereof.

Moreover, a sole made of polymeric material, with at least one macroholethat passes through at the macroportion, is joined so as to form a sealto the membrane and to the supporting layer at the perimeter of themacroportion.

This patent also contains the teaching of structuring the membrane byreinforcing it with protective layers and tear-resistant layers, madefor example of nylon mesh intimately associated with the waterproof andvapor-permeable membrane.

It is also known to reinforce the membrane with high-strength layersmade for example of Kevlar fabric.

Accordingly, the presence of the macrohole allows to define a largesurface of the membrane that is adapted for heat exchange and for theexchange of water vapor with the outside of the shoe; simultaneously,the loss of structural stiffness of the sole is compensated, to contrastthe tear of the waterproof and vapor-permeable membrane, by thesupporting layer. The advantage provided by having a large portion ofsole free for vapor permeation is reduced, however, by the obstacle tothe passage of water vapor that is constituted by the presence of theseveral layers that compose the supporting layer.

A further solution is described in U.S. Pat. No. 6,508,015 by Rauch Max.

This patent discloses a sole provided by means of a two-layer structure,respectively an elastic upper layer, which is permeable to water vapor,and a lower layer, which covers less than 70% of the upper layer andalso acts as support and tread.

In this case, the vapor-permeable activity of the sole is ensured by themicroporous structure of the upper layer and by the open shape of thelower layer.

The microporous structure of the upper layer is not waterproof and ismade for example of sintered plastic material or by means of woven ornon-woven structures made of synthetic material.

Although this solution proposes a large vapor permeation area of thesole, it does not allow to obtain a sole that is effectively waterproof,not even by adopting the refinements suggested in the cited patent,i.e., by treating the microporous material of the upper layer so as tomake it hydrophobic or by providing a further upper layer formed by athin waterproof membrane.

It has in fact been observed that the hydrophobic treatment of thesintered material does not make the upper layer sufficiently or stablywaterproof.

Besides, the association of a waterproof membrane to the upper layer hasthe same drawbacks described as regards the solution that has a membranesupported by a protective layer.

Moreover, a sole provided according to the teaching of this patent, byhaving the microporous upper layer left extensively exposed by the lowersupporting layer, tends to have a progressive degeneration of the upperlayer upon contact with water, which is absorbed by capillary actiontogether with the dirt that said water can convey.

The upper layer, once it is fully impregnated with dirt, is no longervapor-permeable and can rot.

This drawback becomes all the more evident as the porosity of thematerial that constitutes the upper layer increases.

DISCLOSURE OF THE INVENTION

The aim of the present invention is to provide an insert for soles thatis waterproof and vapor-permeable and obviates the drawbacks notedabove, allowing to provide waterproof and vapor-permeable soles that arecapable of dissipating larger quantities of water vapor than currentlyknown soles, at least for an equal durability over time of thewaterproofness characteristic.

Within this aim, an object of the invention is to propose an insert forsoles that simplifies both its assembly and sealing process and itsconstruction, making its structure more flexible, with respect tocurrently known soles.

Another object of the invention is to propose an insert for soles thathas a greater resistance to contamination by fatty substances withrespect to currently known inserts for soles.

Another object of the invention is to provide an insert for soles thathas a greater resistance to degradation by solvents with respect tocurrently known sole inserts.

Another object of the invention is to provide an insert for soles thathas a high mechanical strength, so that there is no need for a furtherelement with perforation-resistance characteristics.

Another object of the invention is to provide an insert for soles thathas a reduced tendency to absorb dirt, so that it can be cleaned moreeasily than currently known inserts.

Another object of the invention is to propose an insert for soles thatis structurally simpler.

Another object of the invention is to provide an insert for soles thatis easy to use and can be manufactured with relatively low costs.

This aim, as well as these and other objects which will become betterapparent hereinafter are achieved by an insert for vapor-permeable andwaterproof soles, characterized in that it has a stratified and cohesivemonolithic sheet-like structure, which comprises a plurality offunctional layers made of a polymeric material that is impermeable towater in the liquid state and permeable to water vapor, at least onefunctional portion of said insert for soles having such a thickness asto give it a penetration resistance of more than approximately 10 N,assessed according to the method presented in chapter 5.8.2 of the ISO20344-2004 standard.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will becomebetter apparent from the description of a preferred but not exclusiveembodiment of the insert for soles according to the invention,illustrated by way of non-limiting example in the accompanying drawings,wherein:

FIG. 1 is an enlarged-scale sectional view of a detail of an insert forsoles, according to the invention;

FIGS. 2 to 7 and 8 to 10 are longitudinal sectional views of sevenstructures of soles in which an insert for soles according to theinvention is used;

FIG. 7 a is a schematic view of a step for providing a sixth one of saidstructure of soles with an insert for soles according to the invention;

FIG. 11 is a perspective view of a third constructive variation of theseventh structure of soles comprising an insert for soles according tothe invention;

FIG. 12 is a partially sectional perspective view of a furtherembodiment of a structure of soles comprising an insert for solesaccording to the invention.

It is noted that anything found to be already known during the patentingprocess is understood not to be claimed and to be the subject of adisclaimer.

WAYS OF CARRYING OUT THE INVENTION

With reference to the figures, the reference numeral 10 generallydesignates an insert for vapor-permeable and waterproof soles, aparticularity of which consists in that it has a stratified and cohesivemonolithic sheet-like structure, comprising a plurality of functionallayers 11 made of a polymeric material that is impermeable to water inthe liquid state and permeable to water vapor.

The term “sheet-like” is used to reference the shape characteristic of astructure that has one dimension that is greatly reduced with respect tothe other two, said dimension being its thickness, which in any case,according to what is commonly understood so as to distinguish a sheetfrom a foil or a membrane, remains substantial.

However, one should not understand that this shape characteristic initself compromises the ability of the insert to bend or flex.

According to the invention, the insert for soles 10 has such a thicknessas to give it a penetration resistance of more than approximately 10 N,assessed according to the method presented in chapter 5.8.2 of the ISO20344-2004 standard related to safety shoes.

Said testing method consists in obtaining a specimen of the material tobe measured and in subjecting it to penetration by a nail with adiameter of 4.50±0.05 mm with a truncated tip and with the indicatedshape and proportions.

The tip of the nail has a minimum hardness of 60 HRC.

The penetration speed of the nail is set to 10±3 mm/min until the tiphas penetrated the specimen completely.

The maximum measured force value, expressed in newtons N, produced bythe penetration of the material is recorded.

The test is performed on four specimens and the lowest of the fourrecorded values is assigned as the penetration resistance value of thetested material.

In a substantially equivalent manner, a first constructive variation ofthe insert for soles according to the invention, not shown in theaccompanying figures, has a functional portion which, according to themethod presented in chapter 5.8.2 of the ISO 20344-2004 standard, has apenetration resistance of more than approximately 10 N.

Moreover, likewise, a second constructive variation of the insert forsoles according to the invention, not shown in the accompanying figures,has more than one of said functional portions.

Said functional portions are preferably adapted to affect one or moreportions of a sole that correspond or corresponds to the regions ofgreater perspiration of the sole of the foot of the user.

Preferably, said polymeric material is macroporous expandedpolytetrafluoroethylene, e-PTFE.

In alternative embodiments of the insert for soles 10, according to theinvention, which are not described further, said polymeric material isselected alternatively among, polyurethane PU, polyethylene PE,polypropylene PP, polyester and the like.

Advantageously, the insert for soles 10 comprises an auxiliary layer 12which is permeable to water vapor and is between functional layers 11.

With particular reference to FIG. 1, such figure illustrates by way ofexample a detail of an insert for soles 10, which comprises twofunctional layers 11 between which an auxiliary layer 12 is interposed.

Depending on the contingent requirements, different embodiments of aninsert for soles according to the invention, not shown in theaccompanying figures, can comprise more than two functional layers 11with auxiliary layers 12 inserted therebetween.

In particular, said auxiliary layers 12 conveniently are made ofmaterial that is structured with fibers according to a woven ornon-woven fabric configuration.

Moreover, the auxiliary layers 12 are conveniently made of a materialselected among

-   -   polyolefins, preferably polyethylene and polypropylene,    -   nylon,    -   polyester,    -   aramid fibers and    -   fluoropolymers.

More particularly, an insert for soles 10 according to the invention canbe provided, for example, by means of a production process that consistsof

-   -   a step for extrusion in paste form,    -   a stratification step,    -   an expansion step and    -   a sintering step.

A step for preparing for extrusion precedes the step for extrusion inpaste form and provides for the mixing of fine powder of PTFE with aliquid lubricant so as to form a paste of PTFE that can be extruded.

In general, said liquid lubricant is of a type capable of wetting thesurface of the fine powder of PTFE and can be removed from it forexample by evaporation or extraction.

Said lubricant is conveniently a substance selected among paraffinnaphtha, white mineral oil, toluene, xylene or other hydrocarbons,alcohols, ketones, esters or mixtures of these substances.

In particular, said lubricant is selected conveniently among those knowncommercially as ISOPAR™ by the Exxon Chemical Company and SHELLSOL byShell Chemicals.

During the extrusion step, the paste of PTFE and liquid lubricant isextruded to obtain a foil.

This foil, during a step for preparation for expansion, is then woundinto a roller and then cold-calendered.

During cold calendering, the foil of extrudate undergoes a thicknessreduction, obtaining a thinner foil that is elongated longitudinally andtransversely and is adapted to constitute a functional layer 11.

The stratification step consists in superimposing, in close contact, acertain number of thin foils thus obtained, still impregnated withliquid lubricant, in order to make them adhere to each other so as topromote the formation of a structure with nodes and fibrils through theinterfaces between the adhered foils, thus obtaining their cohesion.

The cohesion among the foils can be enhanced by means of a compression,for example by calendering, of the stratification of foils, so as toobtain a stratified and cohesive sheet.

Said stratified and cohesive sheet thus obtained is dried, for exampleby evaporation of the liquid lubricant from the extrudate.

During this stratification step it is optionally possible to interposebetween at least two foils at least one intercalary element adapted toconstitute the auxiliary layer 12.

This evaporation is provided by passing the sheet on a roller orcylinder that is kept at a temperature comprised between 200° C. and300° C.

In this manner, the liquid lubricant evaporates rapidly.

As an alternative, the lubricant can be eliminated by extraction, asknown.

Simultaneously or after the drying step, the expansion step is performedand consists in submitting to traction the stratified and cohesive PTFEsheet at least in a longitudinal direction.

This expansion increases further the porosity of the material, furtherincreasing its strength and orienting its fibrils in the direction oftraction. After longitudinal expansion, the stratified and cohesivesheet can be expanded transversely as well, keeping it at a temperaturecomprised for example between 40° C. and 100° C., in order to furtherincrease its porosity.

The sintering step provides for heating the stratified and cohesivesheet to a sintering temperature comprised between the crystallinemelting point and the degradation temperature of the material of whichit is made.

Therefore, in particular, said sintering temperature, for PTFE, iscomprised between 327° C., which is the crystalline melting point and400° C., which is the degradation temperature.

The sintering time, i.e., the time for which said sintering temperatureis maintained, is for example comprised between 10 seconds and 3minutes, so as to obtain sintering of the PTFE polymer.

This sintering is performed by means of the passage of the stratifiedand cohesive sheet on a roller that is heated to the sinteringtemperature, each section of the stratified and cohesive sheet remainingin contact with the roller for the sintering time.

While it passes over said heated roller, the stratified and cohesivesheet is tensioned in order to contrast its shrinkage facilitated by thesintering temperature.

The sintering thus performed increases significantly the strengthproperties of the material but reduces its elasticity.

The directional orientation of the fibrils is mostly determined by thecalendering and expansion directions.

The diameter and the distance of the fibrils of the stratified andcohesive sheet of e-PTFE thus obtained are determined by the dynamics ofthe expansion step, while its porosity depends on the dimensions of theinterstitial spaces between the fibrils formed in the expansion andsintering steps.

The insert for soles 10, according to the invention, is obtained bycutting the stratified and cohesive sheet thus obtained.

According to the invention, an insert for soles 10, as mentioned,conveniently has a thickness that is comprised substantially between 0.5mm and 5 mm and is preferably uniform.

In said first and second constructive variations, the functional portionor portions advantageously has or have a thickness comprisedsubstantially between 0.5 mm and 5 mm which is preferably uniform.

Surprisingly, these thicknesses give the insert for soles 10 accordingto the invention an effective resistance to contamination by fattysubstances and contaminants of expanded PTFE.

Generally, in the presence of intense physical activity and therefore inthe presence of intense perspiration, surface-active agents, as alsodescribed in U.S. Pat. No. 4,194,041, contained in sweat, can in factpenetrate gradually a thin film of expanded PTFE, cover its internalsurfaces and cause a loss of waterproofness thereof due substantially tothe capillary wicking of said substances within the structure of themembrane.

The effect of contamination caused by perspiration on ordinarywaterproof and vapor-permeable membranes and on an insert for solesaccording to the invention was tested by following the proceduredescribed in the cited U.S. Pat. No. 4,194,041.

Human sweat is collected by wringing a wet cotton undershirt used toperform an intense physical effort.

25 ml of liquid sweat are poured into a container that has an openingwith a diameter of 60 mm.

A sample of material of the insert for soles, according to theinvention, is associated so as to seal the opening of the container, bymeans of rubber gaskets.

The container is turned upside down and left to hang in standardatmospheric conditions of 20° C. and 65% relative humidity until thesweat has evaporated completely through the sample.

After two days, needed for all the sweat to disappear from thecontainer, the sample surprisingly shows no signs of contamination.

Vice versa, when testing the same procedure on a sample of traditionale-PTFE membrane, the sample is dark and visibly contaminated.

A second test of the contamination resistance of samples of insert forsoles according to the invention was performed by depositing on saidsamples and on samples of traditional e-PTFE membranes, for comparison,a quantity of 1.0 ml of oil.

The traditional pure e-PTFE membrane showed immediate contamination,losing its white color and becoming transparent, allowing substantialinstantaneous passage of the oil.

Vice versa, the samples of insert for soles, according to the invention,surprisingly did not show changes in color and after 72 hours no passageof oil had occurred.

The insert for soles 10 according to the invention advantageously isimpermeable to water, since it has no through passage points whensubjected to a pressure of at least 1 bar held for at least 30 seconds.

More particularly, waterproofness is assessed as resistance of thesample to penetration of water under pressure, according to the EN1734standard.

A sample of material is fixed to as to close a container provided withan inlet for water under pressure.

The container is filled with water, so as to submit the face of thesample of material that is directed into the container to a hydrostaticpressure of 1.0 bar.

This condition is maintained for 30 seconds.

The sample is blocked between the opening of the container and aretaining ring, both being covered by sealing gaskets made of siliconerubber.

Pressurization is obtained by forcing into the container water thatoriginates from a tank by means of a flow of compressed air.

The compressed air is adjusted by a valve with a pressure gauge on whichthe pressure reached is shown.

The face of the sample that is external to the container is observed.

The absence of crossing points, which consist of the formation, on saidsurface, of drops having a diameter between 1 mm and 1.5 mm, indicatesthe waterproofness of the sample.

If it is necessary in order to avoid the deformation of the sample, agrid is fixed thereon which has a square mesh with a side of no morethan 30 mm and is made of synthetic material and provided by means offilaments measuring 1 to 1.2 mm in diameter.

An insert for soles 10 according to the invention preferably further hasa bursting strength that is at least equal to 8 kgf/cm², determinedaccording to the method described in the ASTM D3786 standard.

This test is aimed at giving indications regarding the mechanicalstrength of the insert, simulating the damage to the material due to anintensification of the pressure that acts on a limited area.

In order to assess bursting strength according to the ASTM D3786standard, a sample with a diameter of 125 mm of test material is placedand blocked above a diaphragm made of synthetic rubber, which has beenmade to expand by a fluid under pressure, up to the bursting point ofthe sample.

The bursting strength of the sample is given the value of the differencebetween the total pressure required to make the sample burst and thecalibration pressure, needed in order to expand the diaphragm; it isdefined and measured in kilograms-force per square centimeter [kgf/cm²].

The test is conducted on ten samples and the average of the measurementsis assumed as the value of the bursting strength of the tested material.

In particular, the hydraulic pressure applied to the synthetic rubberdiaphragm with a diameter of 48 mm and a thickness of 1.80 mm, isobtained by forcing a fluid constituted by 96% pure glycerin, by meansof a piston, into the pressure chamber of the test apparatus.

According to the invention, an insert for soles conveniently has apermeability to water vapor that is at least equal to 9 mg/cm²·h,determined according to the method presented in chapter 6.6 of the ISO20344-2004 standard.

The ISO 20344-2004 standard, in chapter 6.6, “Determination of watervapour permeability”, related to safety shoes, describes a test methodthat consists in fixing a sample of the material being tested so as toclose the opening of a bottle that contains a certain quantity of soliddesiccant, i.e., silica gel.

The bottle is subjected to a strong air stream in a conditionedatmosphere.

The bottle is made to turn so as to stir the solid desiccant andoptimize its action of drying the air contained in the bottle.

The bottle is weighed before and after the test period in order todetermine the mass of humidity that has passed through the material andhas been absorbed by the solid desiccant.

Permeability to water vapor, expressed in milligrams per squarecentimeter per hour [mg/cm²·h] is then calculated on the basis of themass of humidity that has been measured, of the area of the opening ofthe bottle and of the test time.

The insert for soles 10 according to the invention further convenientlyhas a tear strength at least equal to 10 N, determined according to themethod presented in the EN13571 standard.

Tear strength, understood as the average force needed to propagate a cutin a sample, is measured by means of an adjustable dynamometer, whichacts on the sample at a constant crosshead speed of 100 mm/min.

Six samples of the material being tested are submitted to the test,three having the cut arranged parallel to the longitudinal direction,also known as CAL, and defined as the direction of extrusion of thematerial or as the warp direction of the fabric, and three having thecut arranged transversely, also known as PAL, at right angles to thelongitudinal direction.

The sample, which has the characteristic trouser-like shape, is arrangedon a plane between the clamps of the dynamometer so that the cut isperpendicular to the direction of traction.

The sample is subjected to traction until it tears.

The value of the traction force in relation to the movement is recordedand charted.

Tear strength, expressed in newtons N, is calculated as the arithmeticmean of the two arithmetic means TSCAL and TSPAL respectively of thetraction forces recorded in the CAL and PAL tests.

Advantageously, an insert for soles 10, according to the invention, has,for thicknesses thereof comprised between 1 mm and 5 mm, an abrasionresistance that corresponds to a maximum mass loss of 250 mg, determinedaccording to the method presented in the EN12770 standard.

This value of resistance allows to use an insert for soles 10 as a treador, during use, in contact with the ground.

Abrasion resistance, understood as the resistance to wear caused bymechanical action applied to a surface of a sample, in accordance withthe EN 12770 standard, for soles of shoes, is measured with an abrasiontester.

A sample of material to be tested is made to slide longitudinally on adrum with a diameter of 150 mm and a length of 500 mm, which rotates ata speed of 40 rpm and on which an abrasive cloth is fixed.

The advancement of the sample is 4.20 mm for each turn of the drum.

The abrasive cloth, covered with 60-grit aluminum oxide, has an averagethickness of 1 mm and is uniformly associated with the drum.

This abrasive surface must cause a loss of mass of a standard referencerubber comprised between 180 mg and 220 mg, on an abrasion path of 40 m.

The sample is cylindrical, with a diameter of 16 mm and a minimum heightof 6 mm.

The test is performed on three samples and the average of themeasurements is assigned to the abrasion resistance value.

For materials having a density of less than 0.9 grams per cubiccentimeter [g/cm³], the result of the abrasion test is expressed asrelative loss of mass in milligrams [mg]; otherwise, for materialshaving a density of more than 0.9 grams per cubic centimeter [g/cm³],the result is expressed as loss of volume in cubic millimeters [mm³],using the value of the volume mass (density) of the material as well forthe calculation.

In particular, the samples obtained from an insert for soles 10according to the invention, having a density of 0.7 g/cm³, have shown anabrasion resistance, which corresponds to a loss of relative mass ofless than 250 mg, assessed along an abrasive path of 20 m and bydoubling the found value.

This abrasion resistance is comparable to that of an expanded material,such as ethyl vinyl acetate, EVA, or polyurethane, PU, commonly used inthe provision of soles for shoes.

An insert for soles 10 according to the invention, subjected to thetests described above, surprisingly has the characteristics summarizedin the following Table 1.

TABLE 1 Penetration Permeability Bursting Tear Abrasion resistance towater vapor strength strength resistance Thickness [N] [mg/cm² · h]Contamination [kgf/cm²] [N] [mg] 0.6 mm 37 21.7 NO 13.5 10.0 n/a 1.0 mm40 18.7 NO 19.1 57.5 230 1.6 mm 61 12.4 NO 24.1 63.1 210 2.0 mm 29 12.5NO 13.6 40.9 202 2.8 mm 55 9.3 NO 20.7 110.5 240

The use of an insert for soles 10 according to the invention is asfollows.

With particular reference to FIG. 2, an insert for soles 10, accordingto the invention, is used in a first waterproof and vapor-permeable solestructure 100 for shoes.

Said first sole structure 100 comprises a sole body 110, which has alower portion 111, provided with a tread 112, and an upper portion 113that accommodates an insert for soles 10 according to the invention.

Advantageously, the sole body 110 is made of polymeric material,preferably ethyl vinyl acetate, EVA, vulcanized rubber, polyurethane,PU, thermoplastic material, as thermoplastic polyurethane, TPU, orthermoplastic rubber, TR.

A plurality of openings 114 pass through the body of the sole 110 fromits lower portion 111 to its upper portion 113, where their upper ends115 are covered by the insert for soles 10.

A seal 116 is provided at the peripheral region 10 a of the insert forsoles 10 for its waterproof connection to the upper portion 113 of thesole body 110.

The seal 116 can be provided for example by gluing with pressing of thebody of the sole 110 against the insert for soles 10, or by adhesion byway of a method known as high-frequency electrofusion adhesion or byinjection-molding of the body of the sole 110 on the insert for soles10.

Said seal 116 prevents the infiltration of water in the liquid statebetween the insert for soles 10 and the body of the sole 110.

Alternative embodiments of the first sole structure 100, not describedfurther and not shown in the drawings, have one or two of said openings,which are large with respect to the body of the sole and are covered bythe insert for soles according to the invention, sealed perimetricallyto the body of the sole, as described.

With particular reference to FIG. 3, it describes a second solestructure 200, which is co-molded onto an insert for soles 10 accordingto the invention.

Said second sole structure 200 comprises a sole body 210, preferablymade of polymeric material, which has a lower portion 211 provided witha tread 212, and an upper portion 213 that accommodates the insert forsoles 10.

A plurality of openings 214 pass through the sole body 210 from itslower portion 211 to its upper portion 213, where their upper ends 215are covered by the insert for soles 10.

A seal 216 is provided perimetrically to the insert for soles 10 toprovide its waterproof connection to the upper portion 213 of the bodyof the sole 210.

Said seal 216 comprises a perimetric frame 217 that is substantiallyC-shaped, in a single body with the sole body 210, and wraps around theperipheral region 10 a of the insert for soles 10, to which it adheresin a waterproof manner.

In particular, the peripheral region 10 a has three faces in contactwith the perimetric frame 217.

It should be noted that is sufficient for even just one of said faces tobe connected in a waterproof manner to the perimetric frame 217.

The provision of the second structure 200 comprises a step in which thepolymeric material adapted to form the sole body 210 is injected orpoured in the fluid state into a mold in which the insert for soles 10is arranged, adhering thereto and forming the perimetric frame 217.

A third sole structure 300, illustrated by way of non-limiting examplein FIG. 4, is a constructive variation of the first sole 100, where theseal 116 is replaced with a seal 316 that comprises a sealing element317, which is advantageously shaped like a perimetric annular band.

The sealing element 317, in alternative embodiments, not shown in theaccompanying figures, is shaped so as to cover completely the insert forsoles 10 and is perforated at the portion assigned to vapor permeation.

The sealing element 317 is made of waterproof polymeric material,preferably ethyl vinyl acetate, EVA, polyurethane, PU, polyvinylchloride, PVC, or rubber.

The sealing element 317 covers, connecting thereto in a waterproofmanner, at least the adjacent perimetric edges 318 and 319 respectivelyof the insert for soles 10 and of a recess 320 that is shapedcomplementarily thereto, and is adapted to accommodate it and isprovided on the upper portion 113.

With particular reference to FIG. 5, a fourth waterproof andvapor-permeable sole structure 400 comprises a sole body 410, preferablymade of polymeric material, which has a lower portion 411 that isprovided with a tread 412 and an upper portion 413.

A plurality of openings 414 pass through the sole body 410 from itslower portion 411 to its upper portion 413, and upper ends 415 of theopenings 414 lead out from the upper portion 413.

The upper portion 413 is shaped so as to accommodate a composite insert416, which comprises the insert for soles 10 according to the invention.

The composite insert 416 further comprises a perimetric functional rim417 made of polymeric material, which is preassembled to the insert forsoles 10 in a waterproof manner, for example by overmolding, gluing withhydrolysis-resistant adhesives, or by association by high-frequencyelectrofusion.

Conveniently, said perimetric functional rim 417 surmounts theperipheral region 10 a of the insert for soles 10.

The perimetric functional rim 417 allows to protect the stratifiedstructure of the insert for soles 10 in the region of the waterproofseal, in particular, in the presence of auxiliary layers 12 betweenfunctional layers 11, contrasting its delamination.

Preferably, the composite insert 416 further comprises a filler 418,which is superimposed on the insert for soles 10 and is surrounded bythe perimetric functional rim 417 so as to compensate for the stepformed by its portion that surmounts the peripheral region of the insertfor soles 10.

The filler 418 is preferably made of felt or perforated polymericmaterial and conveniently has a significant vapor-permeable structure,which is for example porous, diffusely perforated or lattice-like.

In alternative embodiments, not shown in the accompanying figures, saidperimetric functional rim also affects the central region of the insertfor soles, also performing the function of said filler.

The composite insert 416 is sealed impermeably at least perimetricallyto the upper portion 413 of the sole body 410, conveniently by adhesivebonding.

FIG. 6 illustrates, by way of non-limiting example, a fifth solestructure 500 which constitutes a constructive variation of the fourthsole 400.

Said fifth sole structure 500 comprises a composite insert 516 which issealed at least perimetrically to the body of the sole 410.

The composite insert 516 comprises an insert for soles 10 according tothe invention, whose peripheral region 10 a is associated in awaterproof manner with a C-shaped welt 517, conveniently made ofpolymeric material, which wraps around it.

The welt 517 is preferably molded onto the insert for soles 10, providedby microinjection thereon or by high-frequency electrofusion of a filmof polymeric material selected, for example, between thermoplasticpolyurethane, TPU, and polyvinyl chloride, PVC.

The welt 517 allows to contrast the risk of delamination of thestratified structure of the insert for soles 10, in the region of thewaterproof seal, in particular in the presence of auxiliary layers 12between functional layers 11.

With particular reference to FIG. 7, a sixth sole structure 600comprises a sole body 610, which is composed of a lower component 611,provided with a tread 612, and an upper component 613.

Advantageously, the upper component 613 is made of polymeric material,preferably ethyl vinyl acetate, EVA, or polyurethane, PU.

A plurality of openings 614 pass through the lower component 611, wheretheir upper ends 615 are covered by an insert for soles 10 according tothe invention.

The insert for soles 10, upon its waterproof connection to the sole body610, has its peripheral region 10 a comprised between the lowercomponent 611 and the upper component 613.

Said sixth sole structure 600 can be provided by gluing or overmoldingone of the lower components 611 or upper components 613 to the insertfor soles 10, subsequently gluing or overmolding onto the semi-finishedcomponent the remaining component 611 or 613.

The upper component 613 is conveniently shaped as an annular rim of thevapor-permeable area indicated by the presence of the openings 614 andsurrounds a vapor-permeable or perforated filler 616, which is arrangedabove the insert for soles 10.

It should be noted that both the fourth sole 400 and the sixth sole 600allow to provide openings, respectively 414 and 614, which are shalloweven in the presence of sole of considerable thickness.

The insert for soles 10 in fact is arranged inside the sole structure400 or 600, surmounted by the filler which, during use, is interposedbetween said insert and the foot of the user.

In an alternative constructive solution, not shown in the accompanyingfigures, the upper component 613 covers completely the insert for soles10, providing a central vapor-permeable region that is for examplediffusely perforated, porous or net-like.

In these embodiments, the upper component 613 is provided by directinjection on the upper.

By way of non-limiting example, FIG. 7 a illustrates schematically afinal step of the process for the injection-molding of the uppercomponent 613 onto an upper 620 that is fitted on a last 621 and is sewnto the assembly insole 622, as is per se known.

A mold 623 is closed onto a portion of the upper 620 and onto theassembly insole 622, against which the filler 616 abuts and issuperimposed on the insert for soles 10 connected to the lower component611.

The material for forming the upper component 613 is injected into themold 623 and connects, so as to form a seal, to the peripheral region 10a of the insert for soles 10.

FIGS. 8, 9 and 10 illustrate three constructive variations of a seventhsole structure 700, which comprises a sole body 710 that is shaped likea frame and surrounds an insert for soles 10 according to the inventionembedding at least its peripheral region 10 a, so as to seal thereto ina waterproof manner.

Said seal is obtained advantageously by co-molding of the body of thesole 710 with the insert for soles 10.

As an alternative to co-molding, in different constructive solutions thesole body 710 is glued to the peripheral region of the insert for soles10.

Tread studs 711 made of polymeric material are adapted for resting onthe ground and are associated with the insert for soles 10.

FIG. 8 illustrates by way of example a first variation of the seventhsole 700 in which the tread studs 711 are connected to the insert forsoles 10, for example by adhesive bonding or overmolding and areseparate from the sole body 710.

FIG. 9 illustrates by way of example a second variation of the seventhsole structure 700 provided with the tread studs 711, which are separatefrom the sole body 710 and are provided with hook-shaped pins 712, whichare inserted so as to plug hermetically corresponding accommodationholes 713 provided through the insert for soles 10.

In alternative embodiments of the second variation of the seventh solestructure 700 not shown in the accompanying figures, the tread studs areadvantageously mutually interconnected by an inner grid arranged abovethe insert for soles 10.

Conveniently, the tread studs 711 are formed by their injectionovermolding onto the insert for soles 10.

FIG. 10 illustrates, by way of example, a third variation of the seventhsole structure 700, whose tread studs 711 are connected to the sole body710 by way of transverse ribs 714, which conveniently form a grid on theinsert for soles 10.

With particular reference to FIG. 12, said figure illustrates by way ofnon-limiting example an eighth sole structure 800, which comprises:

-   -   a sole body 810, which has, in its upper portion 811, openings        812 that are adapted to allow the passage of water vapor, and    -   an insert for soles 10, according to the invention, which covers        them in a downward region.

A lower face 13 of the insert for soles 10 forms at least part of thetread of the sole 800.

Moreover, the insert for soles 10 is sealed to the sole body 810 so asto prevent the infiltration of water in the liquid state between them.

In practice it has been found that the invention achieves the intendedaim and objects, providing a waterproof and vapor-permeable insert forsoles that allows to provide vapor-permeable and waterproof soles thatcan dissipate larger quantities of water vapor than currently knownvapor-permeable soles, thanks to the absence of supporting orreinforcement or protection layers, which limit the vapor permeabilityof the sole.

Moreover, an insert for soles, according to the invention, has beenfound to have a higher resistance to contamination by fatty substancesthan currently known inserts for soles, further having, with respect tosaid currently known inserts for soles, a higher resistance todegradation by solvents.

Moreover, an insert for soles according to the invention is structurallysimpler than currently known inserts for soles.

An insert for soles according to the invention further has such aresistance to abrasion as to allow its use in shoes in which it isdirectly in contact with the ground, as a tread.

With respect to currently known inserts for soles, provided withprotective layers of felt and other porous materials that tend to absorbliquids and moisture, an insert for soles according to the inventiondoes not absorb and does not allow stagnation of liquid or wicking ofwater into the sole.

By not requiring the reinforcement and protection of reinforcement andprotection layers, an insert for soles according to the invention has alarger vapor-permeable surface than an insert of the currently knowntype of equal extension, since in this part of the surface it isaffected by glues and adhesives to the reinforcement and protectionlayers which hinder vapor permeation where they are present.

The invention thus conceived is susceptible of numerous modificationsand variations, all of which are within the scope of the appendedclaims; all the details may further be replaced with other technicallyequivalent elements.

In practice, the materials used, so long as they are compatible with thespecific use, as well as the contingent shapes and dimensions, may beany according to requirements and to the state of the art.

The disclosures in European Patent Application No. 09425334.1 from whichthis application claims priority are incorporated herein by reference.

Where technical features and methods mentioned in any claim are followedby reference signs, those reference signs have been included for thesole purpose of increasing the intelligibility of the claims andaccordingly such reference signs do not have any limiting effect on theinterpretation of each element identified by way of example by suchreference signs.

1-28. (canceled)
 29. An insert for vapor-permeable and waterproof soles, having a stratified and cohesive monolithic sheet-like structure, which comprises: a plurality of functional layers made of a polymeric material that is impermeable to water in the liquid state and permeable to water vapor, at least one functional portion of said insert for soles having such a thickness as to give it a penetration resistance of more than approximately 10 N, assessed according to the method presented in chapter 5.8.2 of the ISO 20344-2004 standard.
 30. The insert for soles according to claim 29, wherein said polymeric material is microporous expanded polytetrafluoroethylene, e-PTFE.
 31. The insert for soles according to claim 29, wherein said polymeric material is selected among polyurethane, polyethylene, polypropylene, and polyester.
 32. The insert for soles according to claim 29, further comprising at least one auxiliary layer, which is permeable to water vapor and is interposed between at least two of said functional layers.
 33. The insert for soles according to claim 32, wherein said at least one auxiliary layer is made of a material that is structured in fibers according to a woven or non-woven fabric configuration.
 34. The insert for soles according to claim 32, wherein said at least one auxiliary layer is made of a material selected among polyolefins, nylon, polyester, aramid fibers, and fluoropolymers.
 35. The insert for soles according to claim 34, wherein said polyolefins are selected between polyethylene and polypropylene.
 36. The insert for soles according to claim 29, wherein it has a thickness, at least at said functional portion, substantially between 0.5 mm and 5 mm.
 37. The insert for soles according to claim 29, wherein it is impermeable to water by having, according to the EN1734 standard, no through passage points when subjected to a pressure of at least 1 bar held for at least 30 seconds.
 38. The insert for soles according to claim 29, wherein it has a bursting strength that is at least equal to 8 kgf/cm2, determined according to the ASTM D3786 standard.
 39. The insert for soles according to claim 29, wherein it has a permeability to water vapor that is at least equal to 9 mg/cm2·h, determined according to the method presented in chapter 6.6 of the ISO 20344-2004 standard.
 40. The insert for soles according to claim 29, wherein it has a tear strength of at least 10 N, determined according to the method described in the EN13571 standard.
 41. The insert for soles according to claim 29, wherein it has, for thicknesses thereof between 1 mm and 5 mm, an abrasion resistance that corresponds to a mass loss of less than 250 mg, determined according to the method presented in the EN12770 standard.
 42. The insert for soles according to claim 29, wherein it has a substantially uniform thickness.
 43. A waterproof and vapor-permeable sole structure, comprising: a sole body including, in a lower region, a tread, wherein said sole body includes at least one opening that is adapted for vapor permeation and is covered, in a manner that is impermeable to water in the liquid state, by an insert for soles that has a stratified and cohesive monolithic sheet-like structure, comprising a plurality of functional layers made of a polymeric material that is impermeable to water in the liquid state and permeable to water vapor, at least one functional portion of said insert for soles having such a thickness as to give it a penetration resistance of more than approximately 10 N, evaluated according to the method presented in chapter 5.8.2 of the ISO 20344-2004 standard.
 44. The sole structure according to claim 43, wherein said sole body comprises a lower portion including said tread and an upper portion which accommodates said insert for soles that is sealed to it in a manner that is impermeable to water in the liquid state at its peripheral region.
 45. The sole structure according to claim 43, wherein including a waterproof seal of the peripheral region of said insert for soles to said sole body.
 46. The sole structure according to claim 45, wherein said seal comprises gluing with pressing of said peripheral region to said upper portion.
 47. The sole structure according to claim 45, wherein said seal comprises a perimetric frame, which is in a single body with said sole body, is C-shaped, and surrounds said peripheral region, adhering thereto impermeably at least at a contact face thereof.
 48. The sole structure according to claim 45, wherein said seal is provided by a sealing element that covers, connecting impermeably thereto, at least adjacent perimetric edges respectively of said insert for soles and of said upper portion.
 49. The sole structure according to claim 43, further comprising: a composite insert that is sealed at least perimetrically to said sole body and comprises an insert for soles, a perimetric functional rim that is preassembled impermeably to said insert for soles, said perimetric functional rim surmounting the peripheral region of said insert for soles.
 50. The sole structure according to claim 43, wherein said sole body comprises a lower portion that includes said tread and an upper portion, said insert for soles having a peripheral region that is comprised between said lower portion and said upper portion so as to seal it impermeably to said sole body.
 51. The sole structure according to claim 43, further comprising a filler that covers at least a central region of said insert for soles and has a vapor-permeable structure.
 52. The sole structure according to claim 43, further comprising a sole body that is shaped like a frame that surrounds said insert for soles, embedding at least the peripheral region thereof and sealing itself impermeably thereto, tread studs made of polymeric material, adapted for resting on the ground, being associated with the insert for soles.
 53. The sole structure according to claim 52, wherein said tread studs are separate from said sole body, being jointly connected to said insert for sole.
 54. The sole structure according to claim 52, wherein said tread studs include through pins, which are inserted hermetically in corresponding accommodation holes provided through said insert for soles.
 55. The sole structure according to claim 52, wherein said tread studs are connected to said sole body by transverse ribs that form a grid under said insert for soles.
 56. The sole structure according to claim 43, further comprising a sole body that includes, in an upper portion thereof, said at least one opening covered in a downward region by said insert for soles, of which a lower face forms at least part of said tread, said insert for soles being sealed to said sole body so as to prevent infiltration of water in the liquid state between them. 